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Thread: PSRU for Volks Aeroengine

  1. #1
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    PSRU for Volks Aeroengine

    I posted a question here a couple of weeks ago asking if anyone knew of a source for plans to build a prop speed reduction unit for a Volks conversion. I posted this in the portion of this site that deals with Volks engines and have had no replies yet. If I ask the question again here maybe I'll reach a bigger audience and have better luck. Any replies about doing this, pros and cons versus one of the factory PSRUs would be of interst too. Thanks.

  2. #2
    Moderator Topaz's Avatar
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    It may be simply that nobody here knows of such plans. I'm certainly no expert on the subject, but I understand PSRU's to be very application-specific, so I would tend to doubt that there are 'generic' PSRU's available either as plans or bolt-on for an entire 'class' of engines such as the various VW conversions.

    Great Plains has an optional reduction drive for their kit engines, but I don't know how good it is. The link is here. You might do a search on the forum for PSRU or "reduction" and see what you get. There have been more than a few discussions on the subject, and you might find those useful.

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    Volks PSRU

    Thank you Mr. Topaz for your reply. I've looked at several factory units and would like to try to build one of my own.

    One night I was surfing around looking at Experimental Aircraft websites and I saw a set of plans for sale. You could get a preview look at some of the sheets and it looked pretty good. Naturally I did not bookmark the page and now cannot find it. I'll keep looking.

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    Moderator Topaz's Avatar
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    Well, good luck, then. I hope you re-find that one you located earlier. If you do, you might run it past the forum here again. One or two of the guys have some good knowledge of such things and may know more about the particular model or manufacturer once they have a name for the one in which you're interested.

    What are you planning on powering with the VW?

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    Volkswagen PSRU

    Hey Mr. Topaz

    I did finally manage to track down that web site. The PSRU is called "The Maximizer" and the plans are from Stewart Aircraft.

    www.stewartaircraft.com

    Naturally I'm putting the cart before the horse here working on an engine conversion before building an airframe, but I have a pile of Type 4 Volkswagen engines and need to build something in my "spare" time as I build a new shop building and welding shop. I'm thinking of either a Wittman "Buttercup" or a Zenith STOL CH701. What do you think of either?

    Thanks again.

  6. #6
    Moderator Topaz's Avatar
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    Hi Joel,

    I don't have any experience with either design but I've heard the late Steve Wittman was very well thought-of in the industry and that the Zenith designs also have a good reputation. You might put the question to the forum directly and I'm sure you'll find people with knowledge about the aircraft to help you make your choice. Off the top of my head, the first questions I'd ask is if both of these planes are genuinely able to accomodate a VW engine in terms of power and weight? Would you really use the short/rough field capability of the Zenith or would the higher cruise speed on the Buttercup be more useful in your day-to-day flying? They're probably both fine airplanes, but which meets your needs better (or is there another alternative altogether that is an even better fit?)

    You wouldn't be the first person to choose their airplane based on an engine at-hand! Count yourself lucky that you've got that part of the purchase price 'finished' as it were. Myself, I'd look into Great Plains Aircraft to see about some of their VW conversion kits to 'finish up' your motor. If you're using a PSRU then the crankshaft bearing shouldn't be taking thrust or gyroscopic loads, but there's other things that go into making a successful, reliable, VW conversion for aircraft.

    Marc

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    Choosing an Airplane

    Dear Marc,

    Your comments about engine choice affecting the short field capabilities of an airplane are right on target. The appeal of the Zenith CH 701 is for flying into the short meadow airstrips of Central Idaho that get you into areas of the state otherwise only accessable by one or two day hikes or pack trips with horses.

    I probably won't be the first person to have not only built an engine first, but having done so and put a ton of labor into the airframe, then wanted to upgrade to more power right off the bat.

    Garage is framed and will be done by the Arlington shoe in July. I hope to start building by labor day at the latest.

    Thanks again for your input, I feel like I learn something new about this stuff every day.

    Joel

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